Just curious: I can't think of a single example that a physicist did not had his mouth open in amazement when he learnt that all (OK, lets say the foundations) the math he needs for his brand-new theory had already been paved out long before by mathematicians, possibly just for the fun of it.
Stupid me, of course I can think of an example, I'm always doing it...Knot theory really began with the physical theory of knots in "ether".
Probably should be tagged "small list" but we don't have that one :-)